Japan Geoscience Union Meeting 2018

Presentation information

[EJ] Oral

A (Atmospheric and Hydrospheric Sciences) » A-CG Complex & General

[A-CG39] Multi-scale ocean-atmosphere interaction in the tropical Indo-Pacific region

Mon. May 21, 2018 9:00 AM - 10:30 AM 201B (2F International Conference Hall, Makuhari Messe)

convener:Yukiko Imada(Meteorological Research Institute, Japan Meteorological Agency), Tomoki Tozuka(Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo), Hiroki Tokinaga(京都大学防災研究所, 共同), Yu Kosaka(Research Center for Advanced Science and Technology, University of Tokyo), Chairperson:Tozuka Tomoki, Kosaka Yu(東京大学先端研究所)

9:00 AM - 9:15 AM

[ACG39-01] Contrasting Development and Decay Processes of Indian Ocean Dipoles during Recent Decades

★Invited Papers

*Takanori Horii1, Iwao Ueki1, Kentaro Ando1 (1.Research and Development Center for Global Change (RCGC), Japan Agency for Marine-Earth Science and Technology (JAMSTEC))

Keywords:Indian Ocean Dipole, Eastern Indian Ocean, TRITON Buoy

Using moored buoy data together with satellite and atmospheric reanalysis datasets, we investigated ocean mixed layer temperature (MLT) balance in the eastern Indian Ocean during positive and negative Indian Ocean Dipole (IOD) events observed in recent decades. We mainly focused on TRITON buoy data at 5S, 95E where in situ measurements of more than 15 years by a TRITON buoy were available. Heat balance analysis demonstrated that during the development phase of positive IOD events, horizontal heat advection mainly produced MLT anomalies and that air-sea heat fluxes had a damping effect. During the decay phase, air-sea heat fluxes had a primary role in suppressing MLT anomalies and caused decay of the anomalous IOD conditions. For the development of negative IOD events, warm MLT anomalies are developed via a combination of net air-sea flux and warm advections. During the decay phase, anomalous horizontal advection mainly acted to cool the MLT in the eastern Indian Ocean. The contributions of horizontal heat advections differed in events, which may cause the observed diversity of IOD evolutions. These results suggest that IOD involves variety of feedback processes in positive/negative events and the development/decay phases.